Document Type : Original Article
Authors
1
Department of Microbiology, Faculty of Veterinary Medicine, Necmettin Erbakan University, Konya, Turkey
2
Department of Microbiology, Faculty of Veterinary Medicine, Selcuk University, Konya, Turkey
3
Department of Microbiology, Faculty of Veterinary Medicine, Kafkas University, Kars, Turkey
4
Department of Medical and Clinical Microbiology, Faculty of Medicine, Cyprus International University, Nicosia, Cyprus, Republic of Cyprus
5
Department of Microbiology, Faculty of Veterinary Medicine, Necmettin Erbakan University,Konya, Turkey
10.30466/vrf.2025.2073867.4944
Abstract
Pasteurella multocida and Mannheimia haemolytica are significant bacteria of respiratory tract infections in cattle. Identifying whether these bacteria are commensal or pathogenic is crucial for understanding their role in predisposing calves to respiratory tract infections. This study aimed to determine the prevalence and pathogenic characteristics of P. multocida and M. haemolytica in nasal swab samples of clinically healthy calves in Konya, Turkey, and to assess antibiotic resistance profiles. Using conventional culture methods, 5 samples (1.67%) from 4 different farms were positive for P. multocida and 3 samples (1%) were positive for M. haemolytica. PCR of nasal swab samples yielded P. multocida positivity in 17 (5.67%) samples and M. haemolytica positivity in 13 (4.33%), including all culture-positive samples. While all P. multocida isolates were atypical for the capsule, 18% of the PCR-positive samples were L2, 70% L3A, and 12% L8 serotypes. The ompA, omp87, hghA, and tbpA genes were the most prevalent, while the presence of other virulence genes varied. High rates of ampicillin/cloxacillin (100%) and streptomycin (80%) resistance were observed among the isolates. The rates of serotypes A1 and A6 in M. haemolytica PCR-positive samples were 53.85% and 46.15%, respectively. The ssa-1 gene was detected in 33.33% of the isolates. Moderate resistance to trimethoprim/sulfamethoxazole, streptomycin, and neomycin (66.67%) was recorded. The findings revealed the presence of P. multocida and M. haemolytica with various virulence characteristics and antimicrobial resistance profiles in the nasal microbiota of healthy calves, providing novel insights that could inform improved herd management, disease control, and treatment strategies.
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